The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory captions and links exemplifying features within the Earth system. The community is invited to contribute digital imagery, short captions and relevant links.

Crepuscular Rays Above Merida, Spain

This photo illustrates that while most of us observe crepuscular, or twilight, rays late in the day or early in the morning; they can be seen any time of day if clouds are positioned in such a way to block a portion of sunlight. In addition, we more often view rays when they're "coming up" from the Sun rather than when they're "coming down." The above photo was snapped near Merida, Spain on April 6, 2008, 2 hours and 15 minutes after the Sun had risen. As is the case here, frequently the cloud casting the shadow is above the horizon. The sunlit regions are parts of the atmosphere that usually contain dust or other aerosols, while the dark lanes are in the shadows of clouds.